Interpretation of capillary zone electrophoresis compared with cellulose acetate and agarose gel electrophoresis: reference intervals and diagnostic efficiency in dogs and cats

Background Serum protein electrophoresis is widely used for diagnostic and research purposes. Cellulose acetate (CAE) and agarose gel (AGE) electrophoresis are the most frequently used methods, but capillary zone electrophoresis (CZE) is beginning to be used more in veterinary laboratories. However, reference intervals for CZE in animals and comparison studies with the other electrophoretic techniques are lacking, compromising the diagnostic utility of CZE. Objectives The aims of this study were to compare results obtained using CAE, AGE, and CZE; to establish reference intervals for CZE in dogs and cats; and to assess the capacity of CZE to detect abnormalities identified by AGE. Methods Serum samples from 204 dogs, including 104 healthy animals, and 62 cats, including 28 healthy animals, were analyzed using automated systems for CAE, AGE, and CZE. Descriptive statistics and Passing-Bablok and Bland-Altman tests were used to compare results. For each technique, reference intervals were calculated based on results from healthy animals. Concordance between CZE and AGE in detecting pathologic changes was assessed using Cohen's k coefficient. Results For most protein fractions, values obtained by CAE, AGE, and CZE were significantly different from each other, and constant and proportional errors were often detected. Nevertheless, reference intervals obtained by the 3 techniques overlapped. Moreover, Cohen's k coefficient demonstrated that the capacity of CZE and AGE to detect pathologic changes was comparable. Conclusions CZE performs comparably to AGE and CAE as long as CZE-specific reference intervals are used for interpretation and distinctive visual patterns for albumin, gaps between fractions, and subpeaks found on CZE tracings are recognized. In addition, CZE offers several technical advantages, such as ease of use and complete automation.